FIG. 1 shows a diagram of an exemplary drilling system for drilling an earth formation. Those having ordinary skill in the art will appreciate that a number of other types of drilling systems—for example, deep sea drilling—also exist. Specifically, FIG. 1 shows a diagram of a drilling rig (100) used to turn a drill bit (150) coupled at the distal end (i.e., the end furthest below the ground surface) of a drill pipe (140) in a borehole (145). The drilling system may be used for obtaining oil, natural gas, water, or any other type of material obtainable through drilling.
Specifically, the drill pipe (140) is configured to transmit rotational power generated by a rotary table (125) from the drilling rig (100) to the drill bit (150), and to transmit drilling fluid through the drill pipe's (140) hollow core to the drill bit (150). The drilling fluid may also be referred to as “mud.” A mud pump (180) is used to transmit the mud through a stand pipe (160), hose (155), and kelly (120) into the drill pipe (140).
When drilling, pressure within the borehole (145) may result in a blowout, i.e., an uncontrolled flow of fluids that may reach the ground surface. In some cases, a blowout may be so severe as to cause injury to those operating the drilling rig (100), and may render the drilling rig (100) inoperable. Accordingly, a blowout preventer (130) may be used to control fluid pressure within the borehole (145). Further, the borehole (145) may be reinforced using a casing (135), to prevent collapse due to a blowout or other forces operating on the borehole (145).
The drilling rig (100) may also include other components such as a crown block (105), traveling block (110), swivel (115), and other components not shown.
Mud returning to the surface from the borehole (145) is directed to mud treatment equipment via a mud return line (165). For example, the mud may be directed to a shaker (170) configured to remove drilled solids from the mud. The removed solids are transferred to a reserve pit (175), while the mud is deposited in a mud pit (190). The mud pump (180) pumps the filtered mud from the mud pit (190) via a mud suction line (185), and re-injects the filtered mud into the drilling rig (100).
In some cases, other mud treatment devices may be used. FIG. 2 shows a diagram of an exemplary arrangement of mud treatment devices. As described above, mud arrives at a shaker (210) via a mud return line (205). Solids removed by the shaker are transferred to a reserve pit (215). The mud is then transferred to a degasser (220) configured to remove air or other gasses from the mud. Further, a desander (225), desilter (230), and centrifuge (235) are configured to remove additional solids, of increasing granularity, from the mud. Finally, additives are added to the mud via a mixing hopper (240), and a mud pump (250) pumps the treated mud through a mud suction line (245) to the drilling rig. In some cases, one or more of the aforementioned mud treatment devices may not be used, or may be arranged in a different order.
Operation of the mud treatment devices described above may be referred to, individually or in combination, as a “peripheral drilling operation,” i.e., a drilling-related operation that is not directly associated with rotation of the drill bit. Other types of peripheral drilling operation include, for example, fluid engineering, drilling simulation, pressure control, wellbore cleanup, waste management, etc.